"[W]hat we see... is that... the radiation from all those distant galaxies is redshifted, and the farther away they appear to be... the more redshifted... [T]he usual interpretation... is that they're going away. ...So that they would be approaching the speed of light ...at about 15 billion s away. About 15 billion light-years away... their radiation would go to zero energy because of redshifting."